package  main.java.leetcode.editor.cn;
//2022-10-15 13:47:31
//给你一个二叉树的根节点 root ，按 任意顺序 ，返回所有从根节点到叶子节点的路径。 
//
// 叶子节点 是指没有子节点的节点。 
// 
//
// 示例 1： 
//
// 
//输入：root = [1,2,3,null,5]
//输出：["1->2->5","1->3"]
// 
//
// 示例 2： 
//
// 
//输入：root = [1]
//输出：["1"]
// 
//
// 
//
// 提示： 
//
// 
// 树中节点的数目在范围 [1, 100] 内 
// -100 <= Node.val <= 100 
// 
// Related Topics 树 深度优先搜索 字符串 回溯 二叉树 👍 824 👎 0

import java.util.ArrayList;
import java.util.List;

class BinaryTreePaths {
    public static void main(String[] args) {
        //创建该题目的对象方便调用
        Solution solution = new BinaryTreePaths().new Solution();
    }
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        TreeNode() {}
        TreeNode(int val) { this.val = val; }
        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public List<String> binaryTreePaths(TreeNode root) {
        List<String> result = new ArrayList<>();
        dfs(root,"",result);
        return result;
    }

    public void dfs(TreeNode root,String path,List<String> result){

        if(root == null){
            return;
        }
        StringBuffer sbPath = new StringBuffer(path);  //创建可变字符串
        sbPath.append(Integer.toString(root.val));
        if(root.left == null && root.right == null){  //左右节点均为null,已经遍历到二叉树最底层
            result.add(sbPath.toString());
        }else {
            sbPath.append("->");
            dfs(root.left,sbPath.toString(),result);   //向左遍历
            dfs(root.right,sbPath.toString(),result);   //向右遍历
        }

    }
}
//leetcode submit region end(Prohibit modification and deletion)

}
